I used to fly a Great Planes Cub with the OS70FS.That was about the same size as yours,but probably quite a bit heavier.The 61 FS would be more than enough to fly your Cub.The 70 is quite a bit bigger than the asp61,so if you're wanting to put the cowl on,the 61 would be the better choice.I've just ordered the asp 61fs from hobbyking for my mate.If you want one,put an "email reminder"on it,because they don't seem to keep them in stock.A couple of weeks after I put in the reminder,I got the note to say the engine was in stock.Now it's out of stock again.I'm sure HK waits until they get a few requests for these engines before they order them in.Small price to pay for the discount.Their last price was around $114 US,which is less than half of what my mate would have to pay locally.Although I still own a couple of 2 strokes,I won't buy anything but 4 strokes now.I just love the sound of them,and I find them easier to handle than 2 strokes.Just my $0.02 worth.

HiWould just like to say a Big Thank you to Everyone who took the time to reply.I believe this is the best hobby in the world, with some of the most pleasant and helpful people,ok you get the odd one or two who just wants to fly and do thier own thing,and wont give you the time of day, but thats their choice, let them get on with it.But on the whole I have met some very nice and helpful people who would go out thier way to help you,and it seems that there are many of them on here.Thanks again.Andy